According to Shoigu (their minister of Defence) they'll use the conscripted men in order to secure the existing front-line, which is quite long. Couple that with the incoming referendums during which the regions that now Russia controls in Southern and Eastern Ukraine will vote for an annexation to Russia, which makes me doubtful that the Russian Army will try and make a push further North across the Dnieper or even towards Mykolaiv or Odessa. Not sure though what will happen with the part of Donetsk region that they do no presently control, i.e. to cities like Kramatorsk and Slavyansk. As such, I don't think that the ground being frozen or not will have such a big effect going forward.

Of course, I might be wrong on all this and the Russians launching a new offensive on Kiev and Kharkov.